1. Field
The following description relates to a radio frequency (RF) front end module using a diplexer and a bandpass filter, and a multi-band communication module using the RF front end module.
2. Description of Related Art
A radio frequency (RF) front end includes everything in a receiver which exists between an antenna and an intermediate frequency (IF) state. The RF front end requires a filter through which only a used band frequency is passed, to perform a wireless communication. However, where a plurality of band frequencies are used in a multi-band device, both a filter of each band and an additional component are used to prevent a filter of each band from having an effect on other bands.
In a dual-band device, a diplexer including a low-pass filter and a high-pass filter is a component used to prevent a filter of each band from having a detrimental effect on other bands. However, where at least three frequency bands are used, a combination of the above-described filters may have difficulty in preventing a detrimental effect on other bands. In this instance, a switch device based on a monolithic microwave integrated circuit (MMIC) may be used. The switch device enhances an isolation characteristic between signal paths respectively corresponding to the frequency bands, and as a result, an enhanced attenuation characteristic of a filter is experienced. However, an insertion loss characteristic, which is a loss of signal power resulting from an insertion of a device in a transmission line or optical fiber, decreases as a result of the use of the switch device. In other words, the insertion loss characteristic is inversely proportional to the attenuation characteristic, and thus, the insertion loss characteristic decreases in response to the enhanced attenuation characteristic.
Accordingly, an RF front end module that combines both the convenience of design provided by using a switch and the advantage of using a diplexer, and a multi-band communication module utilizing the RF front end module, are desirable.